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Records Added in August 2020
Records added in August 2020
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Showing records 1 to 25 of 47. [First] Page: 1 2 Last
Incremental Modeling and Monitoring of Embedded CPU-GPU Chips
Oussama Djedidi, Mohand Djeziri
August 29, 2020 (v1)
Keywords: analytical redundancy, embedded systems, Modelling, monitoring, smartphones, system-on-chip
This paper presents a monitoring framework to detect drifts and faults in the behavior of the central processing unit (CPU)-graphics processing unit (GPU) chips powering them. To construct the framework, an incremental model and a fault detection and isolation (FDI) algorithm are hereby proposed. The reference model is composed of a set of interconnected exchangeable subsystems that allows it to be adapted to changes in the structure of the system or operating modes, by replacing or extending its components. It estimates a set of variables characterizing the operating state of the chip from only two global inputs. Then, through analytical redundancy, the estimated variables are compared to the output of the system in the FDI module, which generates alarms in the presence of faults or drifts in the system. Furthermore, the interconnected nature of the model allows for the direct localization and isolation of any detected abnormalities. The implementation of the proposed framework requir... [more]
Accuracy Assessment of RANS Predictions of Active Flow Control for Hydrofoil Cavitation
Chandra Shekhar Pant, Yann Delorme, Steven Frankel
August 29, 2020 (v1)
Keywords: cavitation control, hydrodynamic performance, OpenFOAM
In this work, we numerically investigate the cavitating flow on the scaled-down 2D model of guided vanes. Furthermore, the effects of wall injection on both the cavitation and on the hydrodynamic performance of the guided vane are studied. The numerical simulations are performed using OpenFOAM v1906. We used a 2D k- ω SST model for modeling the turbulence in the present set of simulations. We studied the flow for two angles of attack, viz. 3 ∘ and 9 ∘ . For the 3 ∘ angle of attack, the present numerical work is in good agreement with the previous experimental work, but for the larger angle of attack, because of flow separation, the present simulations do not capture the flow correctly.
Breakup Processes and Droplet Characteristics of Liquid Jets Injected into Low-Speed Air Crossflow
Lingzhen Kong, Tian Lan, Jiaqing Chen, Kuisheng Wang, Huan Sun
August 29, 2020 (v1)
Subject: Other
Keywords: breakup regime, droplet size, droplet velocity, liquid jet, PDA, primary breakup
The breakup processes and droplet characteristics of a liquid jet injected into a low-speed air crossflow in the finite space were experimentally investigated. The liquid jet breakup processes were recorded by high-speed photography, and phase-Doppler anemometry (PDA) was employed to measure the droplet sizes and droplet velocities. Through the instantaneous image observation, the liquid jet breakup mode could be divided into bump breakup, arcade breakup and bag breakup modes, and the experimental regime map of primary breakup processes was summarized. The transition boundaries between different breakup modes were found. The gas Weber number (Weg) could be considered as the most sensitive dimensionless parameter for the breakup mode. There was a Weg transition point, and droplet size distribution was able to change from the oblique-I-type to the C-type with an increase in Weg. The liquid jet Weber number (Wej) had little effect on droplet size distribution, and droplet size was in the... [more]
The Evolution of Cell Free Biomanufacturing
Michael Vilkhovoy, Abhinav Adhikari, Sandra Vadhin, Jeffrey D. Varner
August 29, 2020 (v1)
Subject: Biosystems
Keywords: cell-free protein synthesis, cell-free systems, synthetic biology
Cell-free systems are a widely used research tool in systems and synthetic biology and a promising platform for manufacturing of proteins and chemicals. In the past, cell-free biology was primarily used to better understand fundamental biochemical processes. Notably, E. coli cell-free extracts were used in the 1960s to decipher the sequencing of the genetic code. Since then, the transcription and translation capabilities of cell-free systems have been repeatedly optimized to improve energy efficiency and product yield. Today, cell-free systems, in combination with the rise of synthetic biology, have taken on a new role as a promising technology for just-in-time manufacturing of therapeutically important biologics and high-value small molecules. They have also been implemented at an industrial scale for the production of antibodies and cytokines. In this review, we discuss the evolution of cell-free technologies, in particular advancements in extract preparation, cell-free protein synth... [more]
Development of an Optimal Path Algorithm for Construction Equipment
Hak June Lee, So Young Lim
August 29, 2020 (v1)
Subject: Optimization
Keywords: algorithm, construction, dump, Modelling, optimal path, safety, terrain
The fourth industrial revolution based on information and communication technology (ICT and IoT) is converging into the overall realm of technology, economy and society, creating innovative changes. In line with these changes, research is being actively carried out to integrate information and communication with automation at construction sites. This study was started to analyze problems arising from inefficient operation of construction equipment through analysis of risks arising at construction sites and to provide solutions related to these problems. In order to provide the optimal route of movement of construction equipment, an expert survey was conducted and an algorithm was developed to establish the optimal route of movement by analyzing the weights for each item of the survey. The adequacy of the algorithm was determined by comparing the developed algorithm with the actual data of the construction site in operation, and a safe and productive route as well as problems related to... [more]
A Mini-Review: Needleless Electrospinning of Nanofibers for Pharmaceutical and Biomedical Applications
Ioannis Partheniadis, Ioannis Nikolakakis, Ivo Laidmäe, Jyrki Heinämäki
August 29, 2020 (v1)
Subject: Materials
Keywords: alternatives, drug delivery, nanofibers, needleless electrospinning, process limitations, tissue engineering, ultrasound-enhanced electrospinning
Electrospinning (ES) is a convenient and versatile method for the fabrication of nanofibers and has been utilized in many fields including pharmaceutical and biomedical applications. Conventional ES uses a needle spinneret for the generation of nanofibers and is associated with many limitations and drawbacks (i.e., needle clogging, limited production capacity, and low yield). Needleless electrospinning (NLES) has been proposed to overcome these problems. Within the last two decades (2004−2020), many research articles have been published reporting the use of NLES for the fabrication of polymeric nanofibers intended for drug delivery and biomedical tissue engineering applications. The objective of the present mini-review article is to elucidate the potential of NLES for designing such novel nanofibrous drug delivery systems and tissue engineering constructs. This paper also gives an overview of the key NLES approaches, including the most recently introduced NLES method: ultrasound-enhanc... [more]
Sustainable Catalytic Processes Driven by Graphene-Based Materials
Sergio Navalón, Wee-Jun Ong, Xiaoguang Duan
August 29, 2020 (v1)
Keywords: active sites, advanced oxidation, carbocatalysis, graphene, green chemistry, hydrogenation, organic synthesis
In the recent two decades, graphene-based materials have achieved great successes in catalytic processes towards sustainable production of chemicals, fuels and protection of the environment. In graphene, the carbon atoms are packed into a well-defined sp2-hybridized honeycomb lattice, and can be further constructed into other dimensional allotropes such as fullerene, carbon nanotubes, and aerogels. Graphene-based materials possess appealing optical, thermal, and electronic properties, and the graphitic structure is resistant to extreme conditions. Therefore, the green nature and robust framework make the graphene-based materials highly favourable for chemical reactions. More importantly, the open structure of graphene affords a platform to host a diversity of functional groups, dopants, and structural defects, which have been demonstrated to play crucial roles in catalytic processes. In this perspective, we introduced the potential active sites of graphene in green catalysis and showca... [more]
Sustainable Environmental Management and Valorization Options for Olive Mill Byproducts in the Middle East and North Africa (MENA) Region
Adnan Khdair, Ghaida Abu-Rumman
August 29, 2020 (v1)
Keywords: cleaner production, disposal, Jift, olive mill wastewater, olive Pomace, treatment, valorization, Zibar
Cultivation of olive trees and olive oil production have been considered as a legacy for the Mediterranean region. This custom represents a very important benefit for many nations in terms of wealth and health. However, huge amounts of by-products and waste are generated during olive oil production. This represents a serious environmental impact on land and water bodies if not properly handled. Olive oil extraction generates two waste streams, a solid waste called pomace and olive mill wastewater (OMWW), which has been considered as highly pollutant and phytotoxic waste. These wastes have high disposal costs and predominantly generated from small-scale enterprises that have limited financial resources to treat them properly before discharge to the environment. Besides being a serious environmental problem, OMWW has potential economic value that remains to be utilized such as: fertilizers, valuable antioxidants agents and fatty acids needed in human diet. Also, Olive pomace is a valuabl... [more]
Optimization and Selection of Maintenance Policies in an Electrical Gas Turbine Generator Based on the Hybrid Reliability-Centered Maintenance (RCM) Model
Moath Alrifaey, Tang Sai Hong, Azizan As’arry, Eris Elianddy Supeni, Chun Kit Ang
August 29, 2020 (v1)
Keywords: analytic network process (ANP), co-evolutionary multi-objective particle swarm optimization (CMPSO), developed maintenance decision tree (DMDT), failure modes (FMs), hybrid linguistic failure mode and effect analysis (HL-FMEA), oil and gas plant, Optimization, policy selection, reliability-centered maintenance (RCM)
The electrical generation industry is looking for techniques to precisely determine the proper maintenance policy and schedule of their assets. Reliability-centered maintenance (RCM) is a methodology for choosing what maintenance activities have to be performed to keep the asset working within its designed function. Current developments in RCM models are struggling to solve the drawbacks of traditional RCM with regards to optimization and strategy selection; for instance, traditional RCM handles each failure mode individually with a simple yes or no safety question in which question has the possibility of major error and missing the effect of a combinational failure mode. Hence, in the present study, a hybrid RCM model was proposed to fill these gaps and find the optimal maintenance policies and scheduling by a combination of hybrid linguistic-failure mode and effect analysis (HL-FMEA), the co-evolutionary multi-objective particle swarm optimization (CMPSO) algorithm, an analytic netwo... [more]
Advances in Theoretical and Computational Energy Optimization Processes
Ferdinando Salata, Iacopo Golasi
August 29, 2020 (v1)
Subject: Optimization
Industry, construction and transport are the three sectors that traditionally lead to the highest energy requirements [...]
A 140 MW Solar Thermal Plant in Jordan
Wael Al-Kouz, Ahmad Almuhtady, Nidal Abu-Libdeh, Jamal Nayfeh, Alberto Boretti
August 29, 2020 (v1)
Keywords: concentrated solar power, Energy Storage, Jordan, molten salt, solar energy
This paper aims to compute the performances of a smaller version of Solana power plant, with half the solar field, and 1 of 2 turbines in the power cycle, that can be built in Amman or Ma’an in Jordan. The climate conditions for both Amman and Ma’an are discussed thoroughly in the paper. Furthermore, a preliminary validation exercise performed by using measured monthly average values of electricity production from existing plants, a system advisor model (SAM) is used to predict the performances of the proposed Solana-like plants in Ma’an and Amman. The validation shows a good agreement with the measured data for different existing power plants. The simulation results including the monthly capacity factors suggest the annual operation in Ma’an maybe even better than the operation in Gila Bend, for an annual average capacity factor of about 41% for Ma’an vs. a capacity factor of about 39% for Gila Bend. This is mainly due to the best combination of direct normal irradiance (DNI) and the... [more]
Catalytic and Non-Catalytic Treatment of Industrial Wastewater under the Exposure of Non-Thermal Plasma Jet
Shazia Shukrullah, Warda Bashir, Noor Ul Huda Altaf, Yasin Khan, Abdulrehman Ali Al-Arainy, Toqeer Ahmad Sheikh
August 29, 2020 (v1)
Keywords: contaminated water, DC plasma jet, non-thermal plasma, oxidation, TiO2 catalyst
Freshwater is only 2.5% of the total water on the Earth and rest is contaminated or brackish. Various physical and chemical techniques are being used to purify the contaminated water. This study deals with catalytic plasma treatment of contaminated water collected from different sites of Faisalabad-Pakistan. A non-thermal DC plasma jet technique was used to treat the water samples in the presence of TiO2 catalyst. The plasma-assisted catalytic treatment introduced some oxidative species (O3, H2O2, HO2−, OH−) in the water. These species reacted with pollutants and cause the degradation of harmful contaminants, especially dyes. The degradation of dye sample during plasma treatment was more pronounced as compared to other samples. pH, conductivity and TDS of dye containing sample decreased after catalytic plasma treatment. The degradation of organic pollutants increased due to presence of several oxidants, such as TiO2, ferrous ions and hydrogen peroxide. FT-IR analysis revealed the degra... [more]
Deposition of Boron-Doped Thin CVD Diamond Films from Methane-Triethyl Borate-Hydrogen Gas Mixture
Nikolay Ivanovich Polushin, Alexander Ivanovich Laptev, Boris Vladimirovich Spitsyn, Alexander Evgenievich Alexenko, Alexander Mihailovich Polyansky, Anatoly Lvovich Maslov, Tatiana Vladimirovna Martynova
August 29, 2020 (v1)
Subject: Materials
Keywords: boron, boron-doped diamond, CVD process, doping, single-crystal diamond, thin films, triethyl borate
Boron-doped diamond is a promising semiconductor material that can be used as a sensor and in power electronics. Currently, researchers have obtained thin boron-doped diamond layers due to low film growth rates (2−10 μm/h), with polycrystalline diamond growth on the front and edge planes of thicker crystals, inhomogeneous properties in the growing crystal’s volume, and the presence of different structural defects. One way to reduce structural imperfection is the specification of optimal synthesis conditions, as well as surface etching, to remove diamond polycrystals. Etching can be carried out using various gas compositions, but this operation is conducted with the interruption of the diamond deposition process; therefore, inhomogeneity in the diamond structure appears. The solution to this problem is etching in the process of diamond deposition. To realize this in the present work, we used triethyl borate as a boron-containing substance in the process of boron-doped diamond chemical v... [more]
Kinetics, Isotherms, and Thermodynamic Modeling of the Adsorption of Phosphates from Model Wastewater Using Recycled Brick Waste
Uduakobong A. Edet, Augustine O. Ifelebuegu
August 29, 2020 (v1)
Keywords: Adsorption, brick particles, phosphates, recycle, Wastewater
Phosphates in wastewater at elevated concentrations cause eutrophication of water bodies and their removal from treated wastewater is essential before effluents are discharged to the environment. Phosphates are predominately removed during wastewater treatment by chemical precipitation which is usually expensive and has a significant environmental footprint. The purpose of this study was to investigate the effectiveness of waste recycled bricks as adsorbent for phosphate removal during wastewater treatment. The kinetics, isotherms, and thermodynamics of adsorption were investigated to establish the mechanisms of adsorption. The results showed that adsorption capacities increased with an increase in contact time, adsorbent dosage, and initial phosphate concentration. The kinetic study indicated that adsorption was governed by several mechanisms with various processes dominating different stages of the adsorption. The adsorption process was better represented by the pseudo-second-order k... [more]
Application Solid Laser-Sintered or Machined Ti6Al4V Alloy in Manufacturing of Dental Implants and Dental Prosthetic Restorations According to Dentistry 4.0 Concept
Leszek A. Dobrzański, Lech B. Dobrzański, Anna Achtelik-Franczak, Joanna Dobrzańska
August 29, 2020 (v1)
Subject: Other
Keywords: additive manufacturing, corrosion resistance, dental prosthetic restorations, Dentistry 4.0, energy-dispersive X-ray spectroscope, in-vitro tests, metallography, selective laser sintering, structural X-ray analysis, tensile and bending strength, Ti6Al4V dental alloy, tribological tests
This paper presents a comparison of the impact of milling technology in the computer numerically controlled (CNC) machining centre and selective laser sintering (SLS) and on the structure and properties of solid Ti6Al4V alloy. It has been shown that even small changes in technological conditions in the SLS manufacturing variant significantly affect changes from two to nearly two and a half times in tensile and bending strengths. Both the tensile and bending strength obtained in the most favourable manufacturing variant by the SLS method is over 25% higher than in the case of cast materials subsequently processed by milling. Plug-and-play SLS conditions provide about 60% of the possibilities. Structural, tribological and electrochemical tests were carried out. In vitro biological tests using osteoblasts confirm the good tendency for the proliferation of live cells on the substrate manufactured under the most favourable SLS conditions. The use of SLS additive technology for the manufactu... [more]
Effects of the Microbubble Generation Mode on Hydrodynamic Parameters in Gas−Liquid Bubble Columns
Shanglei Ning, Haibo Jin, Guangxiang He, Lei Ma, Xiaoyan Guo, Rongyue Zhang
August 29, 2020 (v1)
Subject: Other
Keywords: ERT, foam gun, microbubble, optical fiber probe, sintered plate
The hydrodynamics parameters of microbubbles in a bubble column were studied in an air−water system with a range of superficial gas velocity from 0.013 to 0.100 m/s using a differential pressure transmitter, double probe optical fiber probe, and electrical resistance tomography (ERT) technique. Two kinds of microbubble generators (foam gun, sintered plate) were used to generate microbubbles in the bubble column with a diameter of 90 mm, and to compare the effects of different foaming methods on the hydrodynamics parameters in the bubble column. The hydrodynamic behavior of the homogeneous regime and the transition regime was also studied. The results show that, by changing the microbubble-generating device, the hydrodynamic parameters in the column are changed, and both microbubble-generating devices can obtain a higher gas holdup and a narrower chord length distribution. When the foam gun is used as the gas distributor, a higher gas holdup and a narrower average bubble chord length ca... [more]
Considering the Diffusive Effects of Cavitation in a Homogeneous Mixture Model
Yanghui Ye, Cong Dong, Zhiguo Zhang, Yangyang Liang
August 29, 2020 (v1)
Keywords: cavitation, constant-transfer coefficient, diffusion, homogeneous mixture
Homogeneous mixture models are widely used to predict the hydrodynamic cavitation. In this study, the constant-transfer coefficient model is implemented into a homogeneous cavitation model to predict the heat and mass diffusion. Modifications are made to the average bubble temperature and the Peclet number for thermal diffusivity in the constant-transfer coefficient model. The evolutions of a spherical bubble triggered by negative pressure pulse are simulated to evaluate the prediction of heat and mass diffusion by the homogeneous model. The evolutions of three bubbles inside a rectangular tube are simulated, which show good accuracy of the homogeneous model for multibubbles in stationary liquid.
A Feed-Forward Back Propagation Neural Network Approach to Predict the Life Condition of Crude Oil Pipeline
Nagoor Basha Shaik, Srinivasa Rao Pedapati, Syed Ali Ammar Taqvi, A. R. Othman, Faizul Azly Abd Dzubir
August 29, 2020 (v1)
Keywords: artificial neural networks, deterioration, estimated repair factor, life prediction, pipeline
Pipelines are like a lifeline that is vital to a nation’s economic sustainability; as such, pipelines need to be monitored to optimize their performance as well as reduce the product losses incurred in the transportation of petroleum chemicals. A significant number of pipes would be underground; it is of immediate concern to identify and analyse the level of corrosion and assess the quality of a pipe. Therefore, this study intends to present the development of an intelligent model that predicts the condition of crude oil pipeline cantered on specific factors such as metal loss anomalies (over length, width and depth), wall thickness, weld anomalies and pressure flow. The model is developed using Feed-Forward Back Propagation Network (FFBPN) based on historical inspection data from oil and gas fields. The model was trained using the Levenberg-Marquardt algorithm by changing the number of hidden neurons to achieve promising results in terms of maximum Coefficient of determination (R2) va... [more]
Analysis of the Installed Productive Capacity in a Medical Angiography Room through Discrete Event Simulation
Félix Badilla-Murillo, Bernal Vargas-Vargas, Oscar Víquez-Acuña, Justo García-Sanz-Calcedo
August 29, 2020 (v1)
Keywords: discrete events simulation, healthcare engineering, hospital management, installed productive capacity, process model
The installed productive capacity of a healthcare center’s equipment limits the efficient use of its resources. This paper, therefore, analyzes the installed productive capacity of a hospital angiography room and how to optimize patient demand. For this purpose, a Discrete Event Simulation (DES) model based on historical variables from the current system was created using computer software. The authors analyzed 2044 procedures performed between 2014 and 2015 in a hospital in San José, Costa Rica. The model was statistically validated to determine that it does not significantly differ from the current system, considering the DMAIC stages for continuous process improvement. In the current scenario, resource utilization is 0.99, and the waiting list increases every month. The results showed that the current capacity of the service could be doubled, and that resource utilization could be reduced to 0.64 and waiting times by 94%. An increase in service efficiency could be achieved by shorte... [more]
An Analytical Model to Predict the Effects of Suspended Solids in Injected Water on the Oil Displacement Efficiency during Waterflooding
Slavko Nesic, Anatoly Zolotukhin, Vladimir Mitrovic, Dragan Govedarica, Afshin Davarpanah
August 29, 2020 (v1)
Keywords: formation damage, oil displacement, suspended solids, waterflooding
Suspended solids in the injection water cause impairment of water injectivity during waterflooding operations. Suspended solids affect reservoir properties and decrease the permeability of reservoir rocks causing an increase of injection pressure and a decrease in water injectivity. Removal of all suspended solids from injection water is an expensive and economically unfeasible process. To minimize the effects of suspended solids to the formation, it is necessary to determine an impairment mechanism of suspended solids on oil displacement and, therefore, optimize the water treatment process. In this paper, an analytical model that describes the relationship between injection water quality and impairment mechanisms on oil displacement is presented. A formation impairment was calculated, introducing the parameter called impairment ratio, which represents the ratio between suspended solids and pore size distribution of reservoir rock. Based on the impairment ratio, decreases in porosity a... [more]
Numerical Modeling and Analysis of the Performance of an Aluminum-Air Battery with Alkaline Electrolyte
Jiadong Xie, Pan He, Ruijie Zhao, Jianhong Yang
August 29, 2020 (v1)
Keywords: aluminum-air battery, battery performance, electrochemistry, fuel cell, numerical simulation
A numerical model is created to simulate the discharge performance of aluminum-air batteries (AABs) with alkaline electrolyte. The discharge voltage and power density, as a function of the discharge current density, are predicted for the modeled AAB and compared with experimental measurements. A good agreement between model and experiment is found. The effect of various model parameters on the battery performance is studied by adjusting the parameters within a suitable range. The results show that electrolyte thickness is a key factor that can strongly increase the power density and the corresponding current density as the electrolyte thickness decreases. The peak of power density is increased by a factor of two if the electrolyte thickness is reduced from 7 mm to 3 mm. The alkaline concentration is also an important factor, since both the voltage and power density curves are significantly raised as the NaOH concentration is increased from 1 to 4 mol/L. The partial oxygen pressure play... [more]
Dynamic Metabolic Analysis of Cupriavidus necator DSM545 Producing Poly(3-hydroxybutyric acid) from Glycerol
Chenhao Sun, Cristina Pérez-Rivero, Colin Webb, Constantinos Theodoropoulos
August 29, 2020 (v1)
Subject: Biosystems
Keywords: bioprocess, constraint-based stoichiometric modelling, data-driven approach, flux balance analysis, metabolic modelling, poly(3-hydroxybutyric acid), pseudo-steady state, thermodynamics
Cupriavidus necator DSM 545 can utilise glycerol to synthesise poly(3-hydroxybutyric acid) under unbalanced growth conditions, i.e., nitrogen limitation. To improve poly(3-hydroxybutyric acid) (PHB) batch production by C. necator through model-guided bioprocessing or genetic engineering, insights into the dynamic effect of the fermentation conditions on cell metabolism are crucial. In this work, we have used dynamic flux balance analysis (DFBA), a constrained-based stoichiometric modelling approach, to study the metabolic change associated with PHB synthesis during batch cultivation. The model employs the ‘minimisation of all fluxes’ as cellular objectives and measured extracellular fluxes as additional constraints. The mass balance constraints are further adjusted based on thermodynamic considerations. The resultant flux distribution profiles characterise the evolution of metabolic states due to adaptation to dynamic extracellular conditions and provide further insights towards improv... [more]
Thermal Radiations and Mass Transfer Analysis of the Three-Dimensional Magnetite Carreau Fluid Flow Past a Horizontal Surface of Paraboloid of Revolution
T. Abdeljawad, Asad Ullah, Hussam Alrabaiah, Ikramullah, Muhammad Ayaz, Waris Khan, Ilyas Khan, Hidayat Ullah Khan
August 29, 2020 (v1)
Keywords: Brownian motion, chemical reaction, homotopy analysis method (HAM), magnetic field, magnetite–carreau fluid, mass transfer, paraboloid of revolution, thermal radiations
The dynamics of the 3-dimensional flow of magnetized Carreau fluid past a paraboloid surface of revolution is studied through thermal radiation and mass transfer analysis. The impacts of Brownian motion and chemical reaction rate are considered on the flow dynamics. The system of nonlinear PDEs are converted to coupled ODEs by employing suitable transformation relations. The developed ODEs are solved by applying the standard procedure of homotopy analysis method (HAM). The impacts of various interesting parameters on the state variables of the Carreau fluid (velocity components, temperature, concentration, and shear stress) are explained through various graphs and tables. It is found that the horizontal velocity components augment with the rising magnetic parameter and Grashof number values. The fluid temperature augments with the higher values of the pertinent parameters except Prandtl number. The Nusselet number and fluid concentration enhance with the augmenting Brownian motion para... [more]
Optimization of Synthesizing Upright ZnO Rod Arrays with Large Diameters through Response Surface Methodology
Xiaofei Sheng, Yajuan Cheng, Yingming Yao, Zhe Zhao
August 29, 2020 (v1)
Subject: Materials
Keywords: response surface methodology, tri-sodium citrate, ZnO rod arrays
The deposition parameters involved in chemical bath deposition were optimized by a response surface methodology to synthesize upright ZnO rod arrays with large diameters. The effects of the factors on the preferential orientation, aspect ratio, and diameter were determined systematically and efficiently. The results demonstrated that an increased concentration, elevated reaction temperature, prolonged reaction time, and reduced molar ratio of Zn2+ to tri-sodium citrate could increase the diameter and promote the preferential oriented growth along the [002] direction. With the optimized parameters, the ZnO rods were grown almost perfectly vertically with the texture coefficient of 99.62. In the meanwhile, the largest diameter could reach 1.77 μm. The obtained rods were merged together on this condition, and a dense ZnO thin film was formed.
Isolation, Identification, and Optimization of γ-Aminobutyric Acid (GABA)-Producing Bacillus cereus Strain KBC from a Commercial Soy Sauce moromi in Submerged-Liquid Fermentation
Wan Abd Al Qadr Imad Wan-Mohtar, Mohamad Nor Azzimi Sohedein, Mohamad Faizal Ibrahim, Safuan Ab Kadir, Ooi Poh Suan, Alan Wong Weng Loen, Soumaya Sassi, Zul Ilham
August 29, 2020 (v1)
Keywords: fermented food, functional food, GABA, non-protein amino acid, soy sauce fermentation
A new high γ-aminobutyric acid (GABA) producing strain of Bacillus cereus was successfully isolated from soy sauce moromi. This B. cereus strain named KBC shared similar morphological characteristics (Gram-positive, rod-shaped) with the reference B. cereus. 16S rRNA sequence of B. cereus KBC was found to be 99% similar with B. cereus strain OPWW1 under phylogenetic tree analysis. B. cereus KBC cultivated in unoptimized conditions using De Man, Rogosa, Sharpe (MRS) broth was capable of producing 523.74 mg L−1 of GABA within five days of the cultivation period. By using response surface methodology (RSM), pH level, monosodium glutamate (MSG) concentration and temperature were optimized for a high concentration of GABA production. The pH level significantly influenced the GABA production by B. cereus KBC with p-value = 0.0023. GABA production by B. cereus KBC under the optimized condition of pH 7, MSG concentration of 5 g L−1 and temperature of 40 °C resulted in GABA production of 3393.02... [more]
Showing records 1 to 25 of 47. [First] Page: 1 2 Last
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